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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7e8f89a809b4ca1baaa817586befb2c4720de1dd7bb33ef3213e9fbc6e1d71b7' 
  AND token = '4QTBlmEmx1lPWXyzLFVWa8RlTAgwA9xgg+gls4XsI5A=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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