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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'a76b9cf3cab548bfd4cc029a40a34ec061e61b03d3bfb516c611f3ac68f6ee45' 
  AND token = 'RPr5WblNUujtV3QCeJdNWTmftquN2yVTHM1+CNTjZuk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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