SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '0687aea39e191fe3769d1b37345c35fb20247946a71fcbfc89782e01b5d8f37c' 
  AND token = '7SZwwxNdr3ufb3dry8z0fOroQkOMxdNOlSbRvosG2vY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}