SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b4843051505958ac0de93300323842bd3496d5741850c873dd5ea151b54af687' 
  AND token = '7m7v+5WFjYky+0BfOCCWW7A3rUMspNFrN1MORmfKZEQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}