SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b1f00e32973978615ce2730bfb57d46aad7564988a9148e67d4dfd3f7379a44f' 
  AND token = 'tyvqpLGVeTDgmOuDGOSFZ+YxRkkFW3Pw9U9iT9Yzuns=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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