SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'cf3733e2c4983ab880255724e2e6383dcbefc1f097b745bc01d756499d5e62a7' 
  AND token = 'l5jiVTyqqXC6bzOGhsL++AZTGwZ07GvaIMcvb/Qwci0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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