SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4242b7ded8e6fcc3cf496d0f1802689ac0c67d14f33125011a79162187c6561a' 
  AND token = 'AD+blES4qhRfZunZZtQVrm2NxXupQRmnL+5Jv/DXnk0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00038

JSON explain

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