SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'a6b33c551cbd5879e330212c28ea530ab94f3f71920b773786af1f82f548089f' 
  AND token = 'Z84uAhootsjZS4+kSUre1N2q0Jj053l4H/LrMMrlw/Y=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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