SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5678e70bde465e07d3b0f7f910b1c27bcc335cf735f37c622184933fe3d3dc6b' 
  AND token = '2xUaTt5Bw2sXf3J6cgMtpPYimKLe8IFWB7kevCM/Rm4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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