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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'e5a3e8b3aaa1632b278ebff8102bf1c9415fd2e899c71fa62ed06840dfe57bf5' 
  AND token = 'Eln7/B4Y8YG9M1rpttlGkOs08Ew6RmmyLI0qudeTOD0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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