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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'dab2371ff28406705b16bc37a6045edf28b2fd708e55d0acae6e49c13186285a' 
  AND token = 'c1CFNxVXpg0ISPXi2cbqI1pcU3fRrQZinncpZO0ihwo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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