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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '389b36c85dddd448fb64d0271b1ec9fb9a7d021d7616af6b5e9d0403cf76cf5d' 
  AND token = 'NHl0bWPOH409dnBnIUcbKXXJembRWW5p2SGQqxNcxjY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00044

JSON explain

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