SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'a1dfeb72e912799feb29192787c318cc74ae2766ceb420cbf83a6b591e75597b' 
  AND token = 'Q0bhZrmNv1DXRQ2TCu1qC+txHWhPeWagqis1o5mexWU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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