SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '42a74f3a703ebc49a9d6262bb5d2605bcddb040192e31917aebff52e298ade20' 
  AND token = 'YIpF6czNGgwKNPV7Lx44VcsTTRMcKBMj73yrygrH+rE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00045

JSON explain

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