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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b3aaa470f653666016f9ed81079e12cf3bd1ccbf30bc1aaddada97ea1eeec6d7' 
  AND token = '28+oCyHLoaJ+nKSdahRQiZHN5g3fkEkucMrfD6DUtQA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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