SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f75cd0f66918a722e765a18fd31c686b90adc1b8acd17c1861d62979ecb25e7a' 
  AND token = 'alVgNGXd7QB33lepob2iiJ6k7JzIJmf+uqpYbGzJWFY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00043

JSON explain

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