SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '0498f399d4607f598d025fe5107f34a9f6789baa63abc3d3b582c028bc244d7f' 
  AND token = '68f/nGtNc136Nd08QRE/XcNib75/t7tjXNnOyFTpFhc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00038

JSON explain

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