SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '617f1abbc827e0982f914da3416ad8031aef51b6c12ec053fee9cdfe0af71785' 
  AND token = '6n7sfvtyovYI+NmFNu8QU7DEowRfniAVpa196o/ygs4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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