SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '142c6a0fdbb5b66b8738984f484a2c17885f3cf0c1431c5d556a4306027c376c' 
  AND token = '/AuhdFoahJ86Q0UqkCzpmGzVGXDfAxQ++aabPIgR8wU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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