SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '351681df270951550a852e0afe32a801cd6aff0c4cff55013e1df1f9081f8c68' 
  AND token = 'tgK3uJJdcxBxOlXw71nUJm3Jm67RalNH3FMJ3CYFmhE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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