SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '71f18a230644a86392eb30338ca48426d10edfbae97f52c976570192593fc09d' 
  AND token = 'ufofJeaI8bu/fjKP4M0sgEEcNLoweQ1emyOOp2sARTA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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