SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f6d00cffc66c5765a08d973d61392ed3bb04b4bf715e6785c4393b2062eb9ee2' 
  AND token = '5pdEV9OQF/AKKjP2NDhDyAheC9i2n2LLfBO71vVr8nU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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