SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd316948b1d07cdc8bb5e38833ff5bd1204581d4d8d2e517f9168accb9dbcfac1' 
  AND token = 'g4useHbYLRNm2JSP4AuLpM4QKn4RFATJYbK7znHwbQI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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