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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '0c6c3bfc526c61d409cb322bc734f864fa04379599e8a0d37b0b1bef683b29c9' 
  AND token = 'ECgVzSdCXTVMuVveCc4JdpBt3HWSEj7daLF3faz0vRo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}