SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ccd78362412917738cec80847542c6b70afaa54461d5966dbaa10f3459e033bd' 
  AND token = 'onLE1cyZqeNJv/rxmBoVXxAafMsohIH49e0tJZMG/AY=' 
  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"
    }
  }
}