SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '29126f146eb23b26302e9a082636c0eafff3a56279c7060557244c92a5d81bb4' 
  AND token = 'f3QNbjgQZn5y4MbxM1Gd5vTs7uzS7ffPUNBwtMjilXw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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